
import java.io.IOException;

public class Main {

	/**
	 * @param args
	 * @throws IOException
	 */
	public static void main(String[] args) throws IOException {
		java.io.BufferedReader r = new java.io.BufferedReader(
				new java.io.InputStreamReader(System.in));
		int n = Integer.parseInt(r.readLine().trim());
		int count = 0;
		for (int i = 1; i <= n; i++) {
			for (int j = i; j <= n; j++) {
				if (i * j <= n) {
//					 System.out.print(i + "X" + j + ",");
					count++;
				} else {
					break;
				}
			}
		}
		System.out.println(count);
	}
}
